During maintenance work on a gas turbine, it is sometimes necessary to support or lift heavy loads. For example, when replacing a burner, the latter usually has to be removed as a unit out of or from the gas turbine. The loads to be lifted or supported in this case are of such a size that a specialized lifting device has to be used. In addition, numerous gas turbines are designed in such a manner that the maintenance access to certain regions of the components which, during operation of the gas turbine, are acted upon by hot gas has to be realized via those openings which are normally closed off by the burners. In order to perform, for example, replacement work on these components acted upon by hot gas, the burners therefore firstly need to be removed from the gas turbine, so that the maintenance work can be carried out via the burner openings.
A suitable lifting device for maintenance work on a gas turbine is known for example from EP 2 543 868 A2, which device can be fitted to the housing of the compressor.
Alternatively, with some gas turbines it is also possible to make the region acted upon by hot gas in the interior of a gas turbine accessible to the maintenance personnel via a specifically designed maintenance access point, referred to as a manhole. This access is not adequate for all maintenance work, however, and for this reason in many cases cannot replace the removal of other components on the outer housing of the gas turbine in order to make the interior regions accessible.
In order to be able to handle the loads to be lifted or supported during the maintenance work, lifting cranes which can be moved in a suitable manner, for example via a load rail system in the ceiling region of a power plant hall, are typically used. Here, the loads to be supported or lifted by the lifting crane are accommodated in a suitable manner, for example by a cable system that interacts with the lifting crane. The counterforces to be applied for supporting or lifting are suitably diverted by the lifting crane into predefined supports of the power plant hall via the ceiling structure. As an alternative to such ceiling cranes, mobile crane systems can also be used, which firstly have to be brought close to the gas turbine to be maintained, in order subsequently to be able to advantageously provide a crane boom for the maintenance work. Here, the forces necessary for the lifting or supporting of the loads are diverted into the foundation around the gas turbine via the crane boom.
A disadvantage of these mechanisms known from the prior art is that the lifting mechanisms to be provided are of a very complex design. In the case of a ceiling crane, it is, for example, necessary to install a complicated load rail system in the ceiling region, said system being equipped with suitable supports. In the case of mobile cranes, for the purpose of providing mobility, a movement unit which makes it possible to move the lifting device into a suitable maintenance position needs to be provided. Usually, these are movement units equipped with rollers or wheels, which in addition also require a relatively large amount of space and for this reason significantly limit the space that can be made available to the maintenance personnel.
On account of the high costs for such lifting devices, it is also usually not possible for economic reasons to provide more than one lifting device. This again hinders the procedure of the maintenance work, since, for example, it is only possible for a crane used to be available for one lifting or supporting operation, during which period, however, a second lifting or supporting device would possibly be necessary. Furthermore, within the scope of the maintenance work, it is usually essential to leave the lifted or supported loads on the lifting device, since improper setting down of the object in question would only lead to very expensive follow-up measures. In this respect, these objects are often left on the lifting device during the maintenance work, until the object in question can be fitted onto or into the gas turbine again following completion of the maintenance work.
These disadvantages give rise to the technical requirement of proposing a lifting mechanism, or a crane system comprising such a lifting mechanism, which can avoid these disadvantages. In particular, it is desirable for the lifting mechanism to be proposed or the crane system to be able to be provided in a cost-effective and space-saving manner, on the one hand, but, on the other hand, also to be suitable for supporting the loads to be lifted or supported during maintenance work on a gas turbine according to requirement. In particular, the lifting mechanism or the crane system should make it possible to perform maintenance work on the outer housing of the gas turbine in a largely flexible manner and without severe limitations concerning the space available for the maintenance.